Yes, for some people. In the Wegovy 2.4 mg weight trials, fatigue was reported by 11% of people against 5% on placebo [1]. That's about 1 in 9, and roughly 1 in 16 more than placebo. The figures below come from the current US prescribing information, June 2026. For the drug itself, see our Wegovy guide.
About 1 in 9 people on Wegovy 2.4 mg reported fatigue in the trials
The label counts "fatigue and asthenia" together, so the 11% includes weakness as well as tiredness [1]. Headache and dizziness sit close by on the same table. The 7.2 mg column comes from two newer trials with their own placebo group, so compare it with its own placebo column.
| Effect | Placebo (Table 3) | Wegovy 2.4 mg | Placebo (Table 4) | Wegovy 7.2 mg |
|---|---|---|---|---|
| Fatigue, including weakness | 5 | 11 | 5 | 11 |
| Headache | 10 | 14 | 7 | 9 |
| Dizziness | 4 | 8 | 1 | 6 |
| Low blood pressure (adults) | 0.4 | 1.3 | not reported | not reported |
| Fainting (syncope) | 0.2 | 0.8 | not reported | not reported |
| Low blood sugar, type 2 diabetes (Study 3) | 2.5 | 6.2 | not reported | not reported |
Wegovy prescribing information, DailyMed version 19, June 2026: Table 3 (three adult weight trials), Table 4 (Studies 8 and 9, where the 2.4 mg arm had fatigue 9%, headache 8%, dizziness 5%), §6.1 "Hypotension and Syncope" and "Hypoglycemia".
The label points to a few concrete causes of tiredness
The label doesn't explain why fatigue itself happens. It does describe three problems that can make you feel drained, weak or lightheaded [1].
- Low blood sugar, if you have type 2 diabetes. In a Wegovy trial in people with type 2 diabetes, clinically significant low blood sugar affected 6.2% against 2.5% on placebo. The risk is higher with insulin or a sulfonylurea. The Medication Guide's warning signs include weakness, drowsiness, dizziness, shakiness and sweating.
- Low blood pressure and fainting. Low blood pressure was reported in 1.3% of adults on Wegovy against 0.4% on placebo, and fainting in 0.8% against 0.2%. The label specifically says hypotension and orthostatic hypotension were more frequent with antihypertensive medicines; some reactions were associated with fluid loss from stomach side effects.
- Dehydration. Vomiting and diarrhea can drain fluids. The label warns that this can injure the kidneys, especially while the dose is rising.
Each of these is something your prescriber can check for, and if you're on insulin or a sulfonylurea, your prescriber may adjust that medicine when Wegovy starts. Your prescriber decides any change to your Wegovy dose, too. For the stomach side effects that drive dehydration, see Wegovy and nausea.
Headache was reported by 14% of people on Wegovy vs 10% on placebo
Headache is one of Wegovy's common side effects, though the gap over placebo is smaller than for fatigue. At 7.2 mg it was 9% against 7% on placebo [1]. Headache also appears among the postmarketing reports for semaglutide on the Ozempic label, the same molecule at lower doses [2].
The label's low-blood-sugar warning signs also include headache. So if you have type 2 diabetes and a headache comes with shakiness, sweating or confusion, treat it as possible low blood sugar and follow the plan your care team gave you [1].
Dizziness affected 8% vs 4%, and it can travel with low blood pressure
Dizziness was twice as common on Wegovy 2.4 mg as on placebo [1]. It can be a side effect on its own, and it's also a sign of low blood pressure, low blood sugar or dehydration, the three causes above. Dizziness when you stand up, or with fainting, is worth a call to your prescriber, especially if you take blood pressure medicine.
Insomnia isn't on Wegovy's label
Trouble sleeping doesn't appear in Wegovy's side-effect tables or anywhere else in its prescribing information [1]. That doesn't mean no one on Wegovy sleeps badly; absence from the label does not establish whether the drug caused a particular sleep change or what an unreported trial comparison showed. If your sleep changes after starting Wegovy, mention it to your prescriber.
The label doesn't say how long fatigue lasts
There's no duration for tiredness on the label. Nausea, vomiting and diarrhea do have a pattern: a pooled analysis of the STEP 1 to 3 trials found they were generally mild to moderate, transient and most frequent during or shortly after dose escalation [4]. That analysis included Novo Nordisk employees among its authors, and because it studied stomach effects rather than fatigue, it can't tell you how long tiredness lasts.
If tiredness goes on for weeks or gets worse, tell your prescriber so they can look for a cause such as low blood sugar, low blood pressure or another condition. The full side-effect list and its timeline are in Wegovy side effects.
Fainting, a racing heartbeat at rest or confusion need a call
- Fainting or nearly fainting, especially when you stand up.
- A racing or pounding heartbeat at rest that lasts several minutes. The label says Wegovy can raise resting heart rate.
- Shakiness, sweating, confusion or slurred speech if you take insulin or a sulfonylurea (possible low blood sugar).
- Tiredness with vomiting or diarrhea that won't stop (possible dehydration, which the label says can injure the kidneys).
These come from the label's warnings and the Medication Guide [1]. Signs of a serious allergic reaction, such as swelling of the face or throat, need emergency care.